Method for lengthening the machining travel of a machine-tool, device for implementing same and machine-tool using such a device

ABSTRACT

A method for lengthening the machining travel of a machine-tool operating at a very high speed, including a tool-carrying ram mobile on three axes. The method combines with the machining movements of the tool-carrying ram along one or several axes, one or several rectilinear movements of the part to be machined by parametering and digitizing the relative travels and speeds of the part to be machined with respect to the tool-carrying ram. The invention also concerns the device for implementing this method and the machine-tool using such a device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of high speed machining,machine-tools mobile on three axes X, Y and Z, and more particularly tomodifications allowing to improve the machining travel of this type ofmachine.

2. Discussion of the Background

Classically, the tools used in very high speed machining are of therotary type and are placed at the end of a unique tool-carrying rammounted moveable along three axes so as to allow machining on a biglength, a big width and a big depth, as well as tool exchange, grippingand collection functions in magazines conceived for that purpose.

Generally, these machines comprise several main parts, i.e.:

an actual machining station comprising the tool driven in rotation atthe end of the ram and shaping the part to be machined,

a driving station placed near the machining station and constituted by acombination of driving mechanisms ensuring the movements along the axesX, Y, Z of the tool-carrying ram, which also ensures, via an electricspindle, the rotary movement of the tool carried at the end,

a control station collaborating with the driving station according to apre-established instructions program to ensure and to manage thedifferent machining operations and stages of the different parts to bemachined.

The machining station can classically comprise several subsets offeringas many additional functions. Thus, for example, a magazine or a toolstorage device offers several machining tools to the ram mobile on threeaxes coming to leave and take the tools, allowing it to ensure as manymachining functions as possible on a part to be machined. The machiningstation can also comprise a device for exchanging parts to be machinedmanaged by the control module and ensuring the exchange between theparts having just been machined and the ones still to be machined.

With the benefit of its experience in the field of high speed machiningalong three axes and on machines called mono-spindle, the applicant hasconceived high precision machines operating at a high velocity capableof achieving high accelerations and rapidity of function in theirmovement along three axes X, Y and Z by the use of a logical cinematicstructure and innovative driving means, well above that achievable byclassical machining machines. The applicant has noticed that thesemachines, even though they have matched the users requirements up untilnow, can in some situations prove to have limited use in their machiningtravel. In fact, to reply to the new criteria of acceleration andrapidity of function required for very high speed machiningmachine-tools, combined with the concern for compactness of themachines, the travels along the three different axes are comprised inintervals defined by the mechanical or geometrical limits of themachine, which intervals can prove to be too short for someapplications.

The limitation to the travel is a difficulty often found in theconception of machine-tools and several devices can be found in theprior art, ensuring a movement of the part to be machined so as toenable it to get nearer the tool thus avoiding unnecessary travel andtravel times (until the tool is in contact with the part to be machinedand begins the machining stage) which would reduce the machine'sperformance. Nevertheless, no device has been conceived to enable thelengthening of the machining travel of a machining machine-tool of thetype comprising a tool-carrying ram which, ensuring functions of toolgripping, exchange, guidance, and driving moves along three axes X, Yand Z, the three axes forming an orthogonal spatial system of axes and Zbeing the longitudinal axis of the machine and of which the movementsare ensured by linear motors, such as in the case of the machinesconceived by the applicant. In fact, the total freedom of movement ofthe tool-carrying ram combined with its speed due to the use of linearmotors, brings new technical criteria and opens a field of possibilitiesin programming machining on one part to be machined, never previouslyreached. The existing machine-tools using a tool-carrying ram movingalong three axes are, on the whole, less fast and and less precise, anddo not have the dynamic constraints of the ones conceived by theapplicant, in view of their size, higher travels obtained, or lessperforming driving means. In addition, the existing devices which ensurethe movement of a part to be machined are essential to the followingmachining stage because the tools of the classical machine-tools do notmove parallel to the movements of the part to be machined. Thus, on theaxes followed for the movements of the part to be machined, the ram, theheadstock and/or the tool-carrying spindle stay fixed.

The applicant has thus studied the concept of an innovative methodenabling the widening of the capacities of machines' machining travel.The difficulty of such a concept is to offer a device enabling to adaptto a machine already answering perfectly to users' requirements in mostapplications and for most of the parts to be machined so that it is notbuilt-into the machine to avoid an overload when the device is notnecessary. Furthermore, as the increase of the lengths of machiningtravels of a machine-tool have for direct and known consequence toreduce the velocity of the machine, such a device would be set in motionor would start to function only when the part or the side of the part tobe machined (via a machining program) so requires.

SUMMARY OF THE INVENTION

In view of this situation and the specifications required, the applicanthas carried out research aimed at achieving the aforementioned targets.This research has led to the conception of a method which does notreduce the performance of the basic machining machine-tool, integrablebut not built-in to it, and enabling once it has started to function,the machining of parts to be machined which are longer, wider or higher.

According to the main characteristic of the invention, the method forlenghtening the machining travel of a high speed machine-tool of thetype comprising a tool-carrying ram ensuring tool gripping, exchange,guidance and driving and moving along three axes X, Y and Z, the threeaxes forming an orthogonal spatial system of axes and Z being thelongitudinal axis of the machine, the movements being ensured by linearmotors, is remarkable in that it consists in combining to the machiningmovements of the tool-carrying ram along one or several axes, one orseveral rectilinear movements of the part to be machined by parameteringand digitizing the relative travels and speeds of the part to bemachined with respect to the tool-carrying ram.

This method is particularly advantageous as it enables to lengthen theuseful travel of the tool-carrying ram of the machine-tool withoutreducing the dynamic performances. In fact, the mobility on one orseveral axes of the part to be machined with respect to thetool-carrying ram already mobile on these three axes enables not only tobring the part to be machined closer to avoid the non machining timesand reduce the unecessary travel of the tool-carrying ram, which is whatclassically occurred in the devices of the prior art but also to reducethese times of bringing closer by moving the tool-carrying ram and thepart to be machined along parallel axes but in an opposite way thusreducing dead time.

In this precise application, once the part to be machined and thetool-carrying ram are close, several machining configurations arepossible:

either the tool-carrying ram is alone in executing the travel androtatably driving the tool towards the fixed part to be machined,

or the part to be machined is alone in executing the travel in movingtowards the tool-carrying ram fixed with the tool rotatably driven,

or the part to be machined and the tool-carrying ram both move along aparallel direction but in an opposite way.

According to a particularly advantageous characteristic of theinvention, this method consists in parametering and digitizing therelative travels and speeds of the part to be machined with respect tothe travels on axis Z of the tool-carrying ram. This characteristic isparticularly innovative in view of the fact that most machine-tools donot use a tool-carrying ram ensuring a translation on axis Z and theyconsequently do not ensure the suitability between the translation onaxis Z of the tool-carrying ram and a translation parallel with axis Zof the part to be machined in a same direction. This suitability thusrequires the mastering of new parameters.

The invention also concerns the device enabling to implement the methodfor lengthening the machining travel of a high speed machine-tool of thetype comprising a tool-carrying ram moving along three axes X, Y and Z,the three axes forming an orthogonal spatial system of axes and Z beingthe longitudinal axis of the machine, the movements being ensured bylinear motors. This device is remarkable in that it comprises inside themachining zone, a part-carrying clamping subset combined with a drivingsubset ensuring the translation on one or several axes parallel with theaxes of the movements of the tool-carring ram, of the part-carryingclamping subset. Furthermore, the driving subset comprises linear motorswhich drive in translation, synchronising with the movements of thetool-carrying ram on a pair of rails respectively parallel with axes X,Y and Z of the movement of the tool-carrying ram, the part-carryingclamping subset. This consistency in the choice of driving means enablesto produce movements of the parts to be machined as fast as themovements of the tool-carrying ram and avoids to penalize theperformance of the whole of the machine while ensuring a lengthening ofthe travels.

Also, contrary to the devices of the prior art, the movement of the partto be machined is not necessary to the functioning of the machine-toolduring simple machining thus enabling to leave the part to be machinedin fixed position.

The invention also concerns a machining machine-tool adopting the deviceof the invention. This machine-tool is of the type comprising amachining station, a driving station, a control station, the machiningstation taking up at least one mobile set for moving or exchanging theparts to be machined of the invention, the mobile set comprising asealed device isolating the machining station from the outside so as toavoid projections of swarf and is remarkable in that it develops itselfaround the mobile subset, and thus from its own leaktightness device, anisolating device, linked to its frame, separating the machining stationand the elements it is made of from the outside.

This characteristic justifies itself by the new constraints required forthe speed of movement during the movements of the parts to be machined.In fact, such devices for exchanging parts or for moving parts to bemachined, classically comprises a leaktightness device constituted by acover and a separating wall which enables to isolate the machiningstation and to avoid the projection of swarf inside. The movements ofthe device of the invention have forced the designers to ensureleaktightness of the mobile set with respect to the fixed frame of themachine by rubbing. Therefore, the criteria of speed required for themovements of such a device are such that the rubbing must be limited asfar as possible to the detriment of the leaktightness against swarf.Thus, the technological solution of the invention enables to create asecond protection around the elements constituting the machining stationof the machine-tool so as to avoid the spreading of swarf which wouldhave gone through the first cover or through the first protection.Another advantage of this double protection is that, even though theyare protected by their own cover or separating wall, the elementsconstituting the machining station of the machine-tool and moreparticularly the lengthening device of the travel of the invention whichis a mobile device can work out to be dangerous for any nearby handlers,users or technicians. The presence of this second protection thusenables to answer to the safety at work criteria.

The fundamental concepts of the invention having just been detailedhereinabove in their most elementary form, more details andcharacteristics will come out more clearly when reading the descriptionhereinafter using as a non limitative and having regard to the attacheddrawings, a device enabling to implement the method of the invention andof a machine-tool using such a device in accordance with the invention.

This description refers to the enclosed drawings on which:

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a perspective view of a machine-tool comprising a device inaccordance with the invention,

FIG. 2 is a perspective view of the lengthening device of the machiningtravel in accordance with the invention,

FIG. 3 is a perspective view of a machine-tool in accordance with theinvention comprising an added leaktight wall.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As illustrated on the drawing of FIG. 1, the device for lengthening themachining travel referenced as 100 as a whole is placed against amachining machine-tool M operating at high speed of the type comprisinga tool-carrying ram 200 moving along three axes X, Y and Z the threeaxes forming an orthogonal spatial system of axes and Z being thelongitudinal axis of the machine, the movements being ensured by linearmotors. This machining machine-tool classically comprises several mainparts, i.e.:

an actual machining station P1 comprising the tool rotatably driven atthe end of the tool-carrying ram 200 and shaping the part to bemachined,

a driving station P2 situated after the machining station P1 andconstituted by a set of driving mechanisms ensuring the movements alongthe axes X, Y and Z of the tool-carrying ram 200, which also ensures,via an electric spindle, the rotary movement of the tool carried at theend,

a control station P3 collaborating with the driving station P2 accordingto a pre-established instructions program to ensure and to manage thedifferent machining operations and stages of the different parts to bemachined.

The machine-tool M such as illustrated also comprises a tool storagedevice 300 which offers several machining tools to the tool-carrying ram200 coming to take and leave them enabling the tool-carrying ram 200 toensure as many machining functions as possible on a part to be machined.

As illustrated on the drawing of FIG. 2 and according to a particularlyadvantageous characteristic of the invention, the lengthening device 100is made of, inside the machining station P1, a part-carrying clampingsubset 110 combined with a driving subset 120 ensuring the translationparallel with axis Z of the movement of the tool-carrying ram, of thepart-carrying clamping subset 110.

This sole additional translation combined with the movements along threeaxes of the tool-carrying ram 200, enables to answer to the lengtheningneeds of the machining travels along the three classical axes. In fact,according to a non limitative embodiment, the part-carrying clampingsubset 110 comprises a rotation axis, classically called axis B so as topresent, to the tool-carrying ram 200, the different sides of the partto be machined. This rotation movement combined with the Z translationmovement of the part to be machined and the possibilities of toolmovements and tool exchange of the tool-carrying ram 200 enables toachieve, while lengthening the travel, most machining stages.

Furthermore, the mobility of the part-carrying clamping subset 110 hasfor other advantage that it enables its classical rotation along avertical axis (usually called axis B) parallel with axis Y. The speed ofexecution of a machining stage requires the maximum closeness betweenthe part to be machined and the tool-carrying ram 200, such closenesseven though possible, would prevent the rotation of the part when themachining stage changes by direct contact of the part on the tool or onthe tool-carrying ram.

Furthermore, on other configurations, the part-carrying clamping subset110 ensures the support of several parts to be machined separated by aleaktighness wall preventing the projection of machining swarf on theparts not yet machined or on the system of axes of this one when theyare removed from the part-carrying clamping subset. Such leaktightnesswalls are integral with the part-carrying clamping subset 110 and rotateat the same time which implies that the machining station must be wideenough to enable such a rotation. The translation of the part-carryingclamping subset thus enables the rotation of parts and of voluminousmachining sets which would be impossible to use in a device of fixedclassical part-carrying clamping subset which eases greatly the settingof the machining assembly and of the machining station cubicle.

As illustrated on the drawing of FIG. 2 and according to a particularlyadvantageous characteristic of the invention, the driving subset 120comprises linear motors which drive in translation, in synchronisationwith the movements of the tool-carrying ram 200, on a pair of rails 121and 122 parallel with axis Z of the movement of the tool-carrying ram200, the part-carrying clamping subset 110. The advantage of using apair of rails is that it enables the use of linear motors in goodconditions. Furthermore, the combination of linear motors with rails isthe same driving technology as the one used for the movements of thetool-carrying ram, which not only enables to ease the piloting to drivethe part to be machined in synchronisation with those of thetool-carrying ram 200 but also to offer dynamic acceleration and speedcharacteristics of the movements of the part equivalent to those of themovements of the tool-carrying ram 200.

According to a preferred embodiment of the invention, the rails 121 and122 of the travel lengthening device 100 and their driving means, inthis context of the linear motors, are protected against the projectionof swarf by a telescopic cowling 130 (represented in broken line). Inaddition, still in the context of a discharge or protection of thepart-carrying clamping subset 110 against swarf, the telescopic cowling130 comprises along the travel and on each side, a discharge device 140and 150 of the swarf, of the Archimede screw type bringing back theswarf towards the orifice 160 of main discharge of the machiningstation.

According to a particularly judicious characteristic of the invention,the part-carrying clamping subset 110 allows access, when it moves awayfrom the vertical plane of machining of the machine-tool M, to housingswhich ensure the storage of tools of a large dimension arranged so thatthe tool-carrying ram 200 can ensure their gripping. Thus, the toolswhich cannot be stored in the storing device 300 because of their lengthcan be arranged in housings which are not accessible during a simplemachining stage because of the closeness of the part but when this orthese tools are needed in machining, these housings become not onlyaccessible but also useable by the tool-carrying ram 200 by thereversing of the part-carrying clamping subset 110.

According to a particularly advantageous characteristic of theinvention, the device 100 of the invention comprises housings enablingto receive large dimension tools accessible to the tool-carrying ram sothat the latter can ensure their gripping. In this configuration, thedevice 100 enabling to move the part to be machined, ensures thefunction of a tool magazine coming to place in the action range of thetool-carrying ram 200 tools of large dimension needed for the machiningof the part governed on the device 100.

As illustrated on the drawing of FIG. 3, the machining machine-toolreferencd as M as a whole is of the type comprising a machining stationP1, a driving station P2, a control station P3 and of which themachininig station P1 comprises a device 100 for lengthening themachining travel of parts to be machined in accordance with theinvention. As described hereinabove, such mobile devices 100 classicallycomprise a leaktightness device isolating the immediate machining zonearound the tool-carrying ram 200 and that part to be machined to preventthe projection of swarf.

According to a particularly judicious technological choice, this machineM comprises, around the mobile set and its leaktightness device, anadditional leaktightness wall 400, linked to the frame, surrounding themachining station as a whole by separating it from the outside. The aimof this leaktightness wall 400 is to improve leaktightness of themachining station in relation to the outside environment and this fortwo main reasons:

one is that the leaktightness of the machining station is difficult toguaranty when the part-carrying clamping subset such as the invention ismobile,

the other is that handling, or technical interventions can beparticularly dangerous if they are carried out in the vicinity of amobile subset.

According to an advantageous but non limitative embodiment, theleaktightness wall 400 is constituted by an outer cover which extendsthe frame of the machine-tool from its machining station and takes upabout the same outside dimensions at the level of the width and theheight.

This technological choice has another particularly advantageousconsequence: the storage devices and more particularly the rotarystorage devices such as illustrated on the drawing of FIG. 3 andreferenced as 300 and 300′ are classically arranged inside a sealedchamber of dimensions enabling their rotation and enabling thetool-carrying ram to have the stored tools at its disposal. They canmove in the space separating the first wall isolating the immediateenvironment of the machining zone (i.e. the tool, the tool-carrying ramand the part to be machined), the machining zone being defined by theleaktightness device of the part-carrying device and by the wall of themachine-tool machining station, of the second wall 400 thus avoiding theuse of a specific sealed chamber to the tool magazine.

The use of dimensions about equal to the dimensions of the outer frameof the machine-tool M in width and in height has for advantage torespect the compactness criteria required for the dimensions of suchmachines.

As illustrated and according to a particularly advantageouscharacteristic of the invention, the outer cover 400 is parallelepipedicand comprises three openings 410, 420, 430 allowing access to the insideand/or to the elements constituting the machining station. Thus, theopenings 410 and 420 are, according to a preferred embodiment of theinvention, sliding doors enabling according to the sliding travel toallow access progressively:

to the tool housings of the rotary tool magazines 300 and 300′ whenthose are stopped but during machining in view of the presence of thefirst leaktightness wall,

to the mobile device in accordance with the invention.

These different openings are advantageously fitted with inspectionwindows enabling to control the good working order of the machine-tool.

In this precise case, the principle of double cover has for otheradvantage to reduce the shock-proof protection surface which mustsurround according to safety rules the machining station and thus reducethe material costs. This second outer cover indeed enables that only theimmediate machining zone around the tool and the part to be machined areprotected by armoured windows, and steel walls. The rest of themachining station can be protected or isolated from outside by thesecond wall 400 which can be advantageously made from less resistant andthus cheaper materials, more particularly the windows, than those usedfor the first protection.

It is understood that the description and illustration just givenhereinabove of the method, device and machine-tool are given for thepurpose of disclosure and not limitation. It is obvious that variousarrangements of, modifications and improvements to the example hereabove will be possible without departing from the scope of the inventiontaken in its broadest aspects and spirits.

In order to permit better understanding of the drawings, a list of thereference symbols with their explanations is presented here below.

100 . . . Lengthening travel device

110 . . . Part-carrying clamping subset

120 . . . Driving subset

121,122 . . . Guide rails

130 . . . Protection cover of guide rails

140,150 . . . swarf discharge device

160 . . . Main orifice of swarf discharge

200 . . . Tool-carrying ram

300,300′ . . . Storage device

400 . . . Outer cover

410,420,430 . . . Opening accesses of the outer cover

M . . . Machining machine-tool as a whole

P1 . . . Machining station

P2 . . . Driving station

P3 . . . Control station

What is claimed is:
 1. A method for lengthening a machining travel of amachine tool comprising a tool-carrying ram which provides toolgripping, exchange, guidance, driving and moving along three axes X, Yand Z, the three axes forming an orthogonal spatial system of axes and Zbeing a longitudinal axis of the machine-tool, movement of thetool-carrying ram being provided by linear motors, said methodcomprising the step of combining with the machining movements of thetool-carrying ram along one of the three axes, at least one simultaneousmovement of a part to be machined parallel to a rotational axis of thetool-carrying ram and one of the three axes by synchronizing relativetravels and speeds of the part to be machined with respect to those ofthe tool-carrying ram, wherein a first cover made of a first material isprovided around the part to be machined and a second cover made of asecond material is provided around the machine tool and first cover,wherein the first material is different from the second material.
 2. Themethod according to claim 1, WHEREIN the synchronizing is along axis Zof the tool-carrying ram.
 3. The method according to claim 1, furthercomprising the step of discharging swarf using a swarf discharge devicepositioned adjacent to the part.
 4. A device for a machine-tool having atool-carrying ram configured to move along three axes X, Y and Z, thethree axes forming an orthogonal spatial system of axes and Z being alongitudinal axis of the machine-tool, the ram being driven by linearmotors, said device comprising a part-carrying clamping subsetpositioned inside a machining zone and combined with a driving subsetconfigured to translate said clamping subset along an axis parallel witha rotational axis of the ram and one of the three axes, said devicefurther comprising a first cover made of a first material providedaround said machining zone and a second cover made of a second materialprovided around said machine-tool and first cover, wherein said firstmaterial is different from said second material.
 5. The device accordingto claim 4, WHEREIN said driving subset ensures the translation of thepart-carrying clamping subset parallel with axis Z only.
 6. The deviceaccording to claim 4, WHEREIN said part-carrying clamping subset allowsaccess of the tool-carrying ram, when said part-carrying clamping subsetmoves away from a vertical plane of machining of the machine-tool, tohousings which ensure storage of tools arranged so that thetool-carrying ram can ensure gripping of the tools.
 7. The deviceaccording to claim 4, further comprising housings configured to receivetools accessible to the tool-carrying ram so that the tool-carrying ramcan ensure gripping of the tools.
 8. The device according to claim 4,WHEREIN said driving subset comprises linear motors which drive intranslation said part-carrying clamping subset along a pair of railsparallel with the Z axis, and wherein movement of said part-carryingclamping subset is synchronized with the movements of the tool-ram. 9.Device according to claim 8, wherein said driving subset ensures thetranslation of the part-carrying clamping subset parallel with axis Zonly.
 10. The device according to claim 4, further comprising at leastone swarf discharge device positioned adjacent to said part-carryingclamping subset.
 11. A machine-tool comprising: a machining station, adriving station, and a control station, said machining station comprisesat least one mobile set for moving and exchanging a part to be machinedand includes a machine-tool device having a tool-carrying ram configuredto move along three axes X, Y, and Z, the three axes forming anorthogonal spatial system of axes and Z being a longitudinal axis of themachine-tool, the ram being driven by linear motors, said at least onemobile set comprising a part-carrying clamping subset positioned insidea machining zone and combined with a driving subset configured totranslate said clamping subset along an axis parallel with a rotationalaxis of the ram and one of the three axes, said at least one mobile setcomprising a cover made of a first material isolating an immediatemachining zone around the tool carrying ram and around the part so as toavoid projection of swarf, wherein said machine-tool further comprisesan isolating wall made of a second material around the machine-tooldevice and said cover to surround the machining station as a whole andseparate the machining station from an outside, wherein said firstmaterial is different from said second material.
 12. The machiningmachine-tool according to claim 11, WHEREIN said isolating wallcomprises an outer cover which extends from a frame of said machine-tooland has an outside width and an outside height that are identical. 13.The machining machine-tool according to claim 12, WHEREIN the outercover is parallelepipedic and comprises at least one opening allowingaccess to an inside of and to elements of the machining station.
 14. Themachine-tool according to claim 8, and further comprising at least oneswarf discharge device positioned adjacent to said part-carryingclamping subset.